Apparatus for manufacture of welded terminal resistors



April 13, 1954 F. I. ELLIN 2,675,453

APPARATUS FOR MANUFACTURE OF WELDED TERMINAL RESISTORS Filed Feb. 2, 1950 4 Sheets-Sheet l TOR; .17

April 13, 1954 F. ELLlN APPARATUS FOR MANUFACTURE OF WELDED TERMINAL RESISTORS Filed Feb. 2. 1950 4 Sheets-Sheet 2 Axe . INVENTOR.

J60 J75 f PA I APPARATUS FOR MANUFACTURE OF WELDED TERMINAL RESISTORS Filed Feb. 2 1950 F. I. ELLlN April 13, 1954 4 Sheets-Sheet 3 INVENTOR.

MMKU m F. l. ELLIN 2,675,453

APPARATUS FOR MANUFACTURE OF WELDED TERMINAL RESISTORS April 13, 1954 4 Sheets-Sheet 4 Filed Feb. 2, 1950 lEL ENTOR. 0L0; Ila/v Patented Apr. 13, 1954 APPARATUS FOR MANUFACTURE OF WELDED-TERMINAL RESISTOBS Fredrick Isaac Ellin, Chicago, Ill., assignor to David T. Siegel, Glencoe, Ill.

Application February 2, 1950, Serial No. 142,010

This invention is concerned generally with resisters and like electrical units, and more particulary with an improved wire-wound resistor as an article of manufacture and with means and methods for manufacturing the same.

Small electrical resistors, such as are used in electrical circuits of comparatively low power, are of many types. Precision resistors wherein the resistance is controlled within rather close limits are frequently of the wire-wound type. These resistors are generally made by winding resistance wire on a ceramic core. The ends of the wire element are welded or otherwise electrically and mechanically connected to metallic bands encircling the core near the-ends thereof. Each band comprises a strip of she'etmetal bent around the core with the ends extending radially outwardly from the core.and..welded or otherwise secured together to form a terminal lug for mounting the resistor and making electrical ;connections theretd As the barejresistance wire could be readily damaged or shortedout, the wire, core and bands are generally coated with a vitreous enamel and the resistor is then fired to glaze the enamel.

Certain difliculties are encountered in manufacturing resistors ofthe foregoing type. The firing of the resistors oxidizesthe terminal lugs so that they must be cleaned and tinned before lead wires can be soldered to them whenthe resistor is installed. To preventcracking of the core or loosening' of the terminalbands, it is essential that the bands shouldhave'a coeflicient of thermal expansion approximately the sameas that of the core and coating. Metals which meet this requirement are often not suitable for soldering, are not sufficiently. conductive and may possess other undesirable qualities. .Fordiff'erent sizes of resistors, differentlengths of bands and integral lugs must be provided, and there must also be provided a large number of -d-iiferent types of terminal bands to provide the different types and shapes of mounting lugs required.

It is an object of this invention to obviate all of the above enumerated faults and others,'by providing a resistor with terminal bands having only short integral projections extending therefrom and a terminal lug or tab Welded to each projection. 1

Another object of this invention is the provision of means andmethods' for producing the resistor set forth in the foregoing object.

A more specific'object of thisinventiori isthe provision .of a. resistor; havin a terminallpand which has a short integral projection and a terminal lug or tab butt welded thereto. Another specific object of this invention'is the provision of means and methods for manufacturing the resistor set forth in the foregoin'gobject.

The exact dimensions and the positioning of the terminal lug and band extension relative to one another are not of great importance as far as the finished product is, concerned, and it would be needlessly expensive to control'these dimensions and their positioning closely. However, it is desirable that an accurately contiolled engagement be effected betweentheparts' during the welding operation, to insure the formation of a proper welded connection.

An object 'ofthis invention is the provision of means for resiliently placing a terminal. lug against the extension of a resistor terminal band while welding the lug and extension together.

v As noted heretofore, the'firing of the vitreous enamel on a wire wound resistor oxidizes the exposed lugs or extensions of the terminal bands. The oxide is a poor conductor of electricity "It would be possible to insure a good welding contact to the band extensions by mechanical clamps, and if this were done, it would be necessary to control the thickness of the band extensions within rather narrow limits. This would cause unnecessary manufacturing expense as the thickness of the extensions is of no practical significance within widelimits in thefinished product.

An object of this invention is the provison of resilient clampingv means for gripping and insuring good electric contact with the oxidized extension of a resistor terminal band.

A further object of this invention is the provision of means for welding terminal lugs to the integral extensions of the terminal bands of resistors, the means entirely automatic once a cycle of operation is started. f

Other and further objects and advantages of the present invention will be apparent from the following description when taken in conjunction with the accompanying drawings in which:

Figure l is a perspective view of my welding mechanism and resistor at the start of an operational cycle; v

Fig. 2 is a fragmentry top view partially in section taken along the line-2 -2 of Fig. 1;

Fig. 3 is a cross-sectional view taken along the line 33 of Fig, lg V v r Fig. 4 is a sectional view taken along the 9454. Pie-" Fig. 5 is a view partly in section taken alon the line 5-5 of Fig. 2;

Fig. 6 is a side elevational view partially in section taken along line 6-6 of Fig. 3;

Fig. 7 is a sectional View of a resistor and the jaws for clamping the terminal band extension and the terminal lug at the start of an operational cycle; I (I Fig. 8 is a view similar to Fig. 7 takeniat a later time in a cycle;

Fig. 9 is a sectional view taken along the line 9-9 of Fig. 8; a

Fig. 10 is a sectional view taken along the line Ill-l8 ofFig.7; f

Fig. 11 is a perspective view of the jaws for securing the terminal lug during welding f Fig. 12 is a view of the jaws for securing the terminal band extension;

Fig. 13 is a perspective view of one of my resistors prior to the welding of the terminal lugs thereon, the vitreous enamel coating being omitted for clarity of illustration;

Fig. 14 is a view similar to Fig. 13 after the lugs or tabs have been welded on;

Fig. 15 is a fragmentary view of a resistor showing a difierent type of tab or terminal lug;

Fig. 16 is a view similar to Fig. 15 showing another type of tab or lug;

Fig. 17 is a cross sectional view as taken along the line I1I'| of Fig. 14, the vitreous enamel being shown;

Fig. 18 is a schematic wiring diagram of an electrical control circuit for operating my mechanism; and

Fig. 19 is a pneumatic circuit operated by the electrical circuit shown in Fig. 18 and operating my mechanism.

Stated briefly, the method and mechanism for welding terminal lugs or tabs to terminal band extensions or projections of resistors includes structure for supporting a resistor and resiliently gripping a terminal band extension, and structure for resiliently gripping 9. lug to be welded thereto. The band extension is forced against the lug by resilient pressure and a welding current is supplied between the band extension and tab. At the same time a hydrogen flame is played on the weld to prevent oxidation of the weld and tab surfaces in order to produce a finished prodnot which is neat in appearance and which may be soldered readily. Upon completion of the weld, the welding current is turned off and is soon followed by extinction of the hydrogen flame. The lug and band extension are then released and the operating parts are returned to their initial positions.

For best understanding of this invention, attention should first be directed to Figs. 13-17 wherein resistors and various terminal lugs are shown. In Fig. 13 is shown a resistor 28 comprising a ceramic core 22 on which is wound a wire resistance element 24. The wire is welded or otherwise secured at each end to terminal bands 26 and 28. The bands comprise strips of sheet metal which are bent around the core and have upstanding extensions or projections 38 and 32 which comprise the ends of the bands bent upwardly and spot welded as shown at84 in Fig. 17 or otherwise affixed together. The resistor is shown in Fig. 14 with terminal lugs or tabs 36 and 38 butt welded to the extensions and 32, respectively. In Fig. 14 the terminal lugs are shown as being of substantially the same width as the bands 26 and 28. A fragment of a similar resistor 20 is shown in Fig. 15 wherein a tab 36a is welded to an identical extension 38 on a. band 26. In this case the lug is of greater width than the band for different installation requirements. A different type of tab 361) which is wider than the band 26 and extension 30 and is essentially L-shaped for still different installation requirements is shown in Fig. 16. In each of Figs. 13-16, and in the apparatus views subsequently to be described, the vitreous enamel coating has been omitted so that the winding of the resistance element and the placement of the terminal band may be seen readily. It is to be understood, however, that normally prior to the tab welding operations, the vitreous enamel would cover the wire winding and the terminal bands but not the extensions 38, 32, as shown at 31 in Fig. 17, and that these extensions would be in oxidized condition by the firing of the enamel.

For an understanding of the means and method of producing the resistor shown and described, reference should be had next to Figs. 1-12 and more particularly first to Fig. 1 wherein a resistor 28 having one tab 88 already welded in place is shown in position on the welding mechanism for the start of an operational cycle to weld the other tab 36 in place. The mechanism comprises a table 48 having situated near the rear end thereof a bifurcated block 42 secured by means such as screws 44 (Fig. 6). As will be apparent hereinafter, the table 40 is preferably made of some insulating material which may, for example, be wood. The table 48 may be mounted or supported in any desirable manner and support means are not shown except for clamping arms 46.

The means for holding the resistor comprises an arm 48 of conductive material which is preferably of low resistance, pivotally secured within the arms of the block 42 by a pintle 50. Welding current is supplied to the arm 48 by means of a cable 52 and terminal connection 54 which may be secured by means such as a screw 56 to the rear end of the arm. A pin 58 extends rearwardly from the arm 48 (Fig. 6) and a tension spring 60 is connected between this pin and a spring mounting bracket 62 secured to the underside of the table as by screws 64 normally to bias the arm upwardly. An adjustable stop 66 comprising a bracket 68 and set screw 18 may be secured to the block 42 to limit the upward movement of the arm 48. The free end of the arm 48 includes a head 12 to which is secured a mandrel 14 on which the resistor is placed. The mandrel is preferably removable so that a single machine may be adapted to accommodate a variety of resistors.

To effect the proper angular positioning of the resistor terminal band extension to be welded, a clamp 16 (Fig. 3) is secured by an arm I8 forwardly of the head 12. The clamp comprises a supporting member 88 fixedly secured to the arm 18 and a jaw 82 which is secured by a screw 84 fitting through an elongated slot in the jaw 82 and threaded into the support member 88 and is adjusted by a screw 86 which may be locked in place by a jam nut 88. For convenience of adjustment the screw head and nut may both be knurled. The band extension to be welded is arranged to be clamped against the jaw 82, by means subsequently to be described, and positioned thereby for the welding operation.

Means is provided for depressing arm 48, and simultaneously clamping the resistor band extension. More particularly, adjacent the head 12 the arm 48 carries a bifurcated bracket 88 in- 5 eluding anupper arm 92 and alower arm 94, the former extending farther than the latter and carrying an adjustable screw 96 which may be locked in position by a jam nut 98. The screw 96 abuts against a stop I secured to the table 40 to limit the downward movement of the arm 48. Adjustable screws I92 and I04 are carried opposite one another by the upper and lower arms respectively for abutment by a finger I06 radially secured to and operable to limit the rocking motion of a shaft I08. The shaft I08 is journalled for pivotal movement in the arm 68, the portion of the shaft passing through the arm 48 being of reduced diameter as at Hi! to preclude axial motion of the shaft in one direction. The other end of the shaft is reduced in diameter to an even greater extent and is provided adjacent its extremity with an operating arm II2 to which it is secured as by being pinned to a collar II4 integral with the arm I I2 for rotation therewith. A cam member H6 is secured to the arm I I2 (Figs. 2 and adjacent the rear end thereof. A clamping arm H8 is pivotally secured by the bracket 90 and carries at its rear end a roller I20 abutting against the cam IE6.

' A coil spring I22 carried within a recess I24 in the arm 48 abuts against the clamping arm II8 to force the roller I20 against the cam II6. A screw I26 threaded through the arm II8 prevents displacement of the abutting end of the spring I22. The opposite end of the arm II8 carries a clamp I28 comprising an adjustable jaw similar to the jaw 82 of the clamp 16. By means of the connections described, as arm I I2 is actuated to lower the main support arm 48, cam II6 operates to project clamp I28 against the terminal band extension.

The means for operating arm II2 comprises a double acting air cylinder I30 containing a piston mounted on a bracket I32 secured to the table 40 by means such as bolts I34. The cylinder I30 is provided with air supply lines I36 and I38 and has the piston rod I40 extending downwardly from its lower end. The piston rod I40 has a connection I4I for determining its length and is provided at its lower end with a connection including a transverse stub shaft I42 slidably and rotatably secured within an elongated slot I44, Fig. 6, adiacent the end of the arm H2 opposite from the cam II6.

The remainder of the welding mechanism is located on the table 48 and includes a terminal lug or tab securing nest I46 including a cylinder I48 (Figs. 1, 3 and 6) projecting through the table and secured thereto as by a collar I58 which may be integral with the cylinder or affixed to it in any desired manner. The collar is in turn secured to the table by any desirable means such as by screws I52. The bottom of the cylinder is closed by an end piece I54 which carries an adiusting screw I 56 which may be locked in position by means of a set screw I58.

The ad usting screw I56 impinges u on a spring .its extreme lower end the member I64 is provided with an extending portion I10 of small diameter to locate the spring I62. The lower portion of the member I64 may be provided with a central bore I12 in order to reduce the weight and inertia of the member. The member I64 is bifurcated at its upper end and carries a clamp or jaw I14 fixed thereto as by pins or screws I16 passing through the member I64 and the jaw I14. A tongue I18 extends laterally from the jaw I14 and has a cable I secured thereto. A second clamp or jaw I82 is pivotally secured to the member I64 in opposed relation to the jaw I14 as by a diametral pin I84.

The member I64 is radially apertured a short distance below the table 40 to threadedly receive the reduced end portion I86 of a spring loaded cylinder I88. The spring is retained in the cylinder by an end piece I90 which may be threaded into the cylinder or secured by a pin I92 or secured in any other desired fashion. The spring I94 forces a piston I96 and a piston rod I68 normally to the right as seen in Fig. 3. The piston rod has its extremity abutting against the lower end of the clamp or jaw I82 to force the upper part of the jaw into clamping engagement with the jaw I14. The cylinder I49 is provided with an elongated longitudinal aperture 200 accommodating the spring loaded cylinder I68 for up and down movement.

A short distance to the right of the tab receiving nest I46 as seen in Fig. 3 is a double acting pneumatic cylinder 202 secured to the under side of the table 40 by a mounting bracket 204 and screws 206. A piston rod 208 extends from the cylinder 202 toward the nest I46 and has secured to it a bifurcated bracket 2 I0 in sliding engagement with the underside of the table 40. The bifurcated bracket 2I0 carries a roller 2I2 on a horizontal axle 2I4. The roller 2I2 at all times abuts against the flat end of a solid cylindrical member 2I6, Fig. 4, having a reduced end portion 2I8 threaded into the clamp or jaw I82 opposite the piston rod I98. The cylindrical member 2I6 fits within an elongated longitudinal aperture 220 in the cylinder I48 for up and down movement. It should be noted that such movement is sufficiently restricted that a horizontal line through the center of the roller 2|? always passes through the cylinder 2I6.

In Fig. 1 may be seen a nozzle 222 for discharging hydrogen directly above the nest I46 and upon the weld as it is being made. A spark ignitor 224 is carried by the table adjacent the nozzle 222 to ignite the hydrogen jet to prevent oxidation of the weld and terminal or tab surfaces to produce a clean neat appearing product which may be soldered readily.

Before proceeding to the control circuits and the operation of the apparatus, attention should be directed to Figs. 11 and 12 for further details of'the jaws I14 and I82 and the jaws 82 and I28. Aside from the details already disclosed, it will be seen that the jaw I14 is provided at its upper end with a rectangular recess 226 which facilitates the placement of a terminal lug or tab in position to be welded. An extending section 226 on the upper portion of the jaw I82 cooperates with the recess 226 to clamp a tab as will be apparent hereinafter. The clamp 82 may be seen in Fig. 12 to have an extending portion 239 of comparatively small vertical dimension in order best to clamp a band extension 60, of the resistor. The extending portion 265. is provided with a clamping surface 232 and a tongue 234 extending therebeyond. The tongue 284 is narrower in its lateral dimension than the tending portion 230.

clamping surface 232 so that a terminal band extension may be clamped centrally of the ex- The cooperating clamp I28 is provided with a thin extending portion similar to the portion 230 of the clamp 82. portion 236 is provided with a clamping suriace 238 of the same lateral dimension as the clamping surface 232 and with a notch 240 to receive the tongue 234.

The pneumatic cylinders I30 and 202 along with their associated controls are shown in '19. A storage tank 242 is supplied with air under pressure from any suitable pump which is not shown. A supply line 244 leads from the tank 242 to a four-way valve 246 controlling the operation of the cylinder I30. A control arm 24? extends from the valve 246 and is pivotally connected to the plunger 250 of a solenoid 252. The plunger 250 is normally pulled away from the solenoid 252 by a tension spring 256 anchored to any suitable fixed point 256. When the valve arm 248 is urged to the left as shown in Fig. 19, the lower end of the cylinder I30 is supplied with air under pressure through the line 244, the valve 246 and a supply line 258 at the same time the upper portion of the cylinder I30 is connected through a line 260 and the valve 246 to an exhaust line or port 262. When the valve arm 248 is moved to the right by energization of the solenoid 252, the upper end of the cylinder I30 is supplied with air under pressure through the line 260, valve 246 and line 244 while the lower end of the cylinder is open to the atmosphere through the line 258, valve 246 and exhaust 262, so that the piston and piston rod [40 are forced downwardly.

The cylinder 202 is supplied with air under pressure from the tank 242 through a supply line 264, a four-way valve 266 and either of lines 258 and 210. A valve arm 212 extends from the valve 266 and is pivotally connected to the plunger 214 of a solenoid 216. The plunger is normally held down as seen in Fig. 19 by a tension spring 218 secured to any fixed point 280. In

this position the valve ports are so oriented that I the line 210 is connected to the line 264 while the line 268 is open to the atmosphere through the exhaust port 262 so that the piston rod 208 is urged to the left and the jaws I14 and I82 are held out of clamping engagement. When the valve arm 212 is raised due to energization of the solenoid 216, the connections are reverse so that the left end of the cylinder 202 is supplied with air under pressure while the right end is open to the atmosphere to move the piston andgu piston rod 208 to the right to release the jaws I14, I82, permitting the spring I94 to act to bring the jaws into clamping engagement.

An electrical control circuit is disclosed in Fig. 18 whereby the operation of the apparatus,

is rendered automatic from start to finish of a welding cycle. Power is supplied through a pair of supply lines LI and L2; and the solenoids 252 and 216 previously referred to are connected in parallel to the line L2 and are in series with a switch driving motor 284 which is connected through push button switches 286 and 288 to the supply line LI. The switches 286 and 288 are located sufliciently far apart that both hands must be used to actuate them so that it is impossible for an operator to get his hands caught in the machinery. A switch arm 290 is connected to the line LI through a line 292 and is driven in a clockwise direction by the motor 284 as is indicated by the dashed line 284. The motor driven switch circuit extends from line .LI and is completed to line L2 through a plurality of arcuate contacts, there also being an insulating or non-connected contact 296. A contact 268 is connected through lead wire 300 and lead wire 302 to an auxiliary switch actuating solenoid 304. The circuit from the solenoid 304 is completed by a line 306 to the line L2. Energization of the solenoid 304 pulls a switch member 308 into contact with switch points 3) and 3l2 to complete a circuit in parallel with the push buttons 286 and 288. A pilot light 3I4 is connected in parallel with the solenoid 304 and may be a distinctive color such as red or amber to indicate that the welding apparatus is operating automatically. Arcuate contact 3I6 is connected to a relay 3I8 controlling the welding current and the relay 3I8 is in turn connected to the line L2. Arcuate contact 320 is connected to a relay 322 controlling the hydrogen jet and the electrical circuit is completed through the relay 322 to the line L2. The remaining contact 324 is connected to a relay 326 controlling the spark gap to ignite the hydrogen jet and the relay 326 is in turn connected to the line L2.

To carry out a welding operation, the operator places a terminal lug or tab 36 loosely between the jaws I14 and I82 (Figs. 1 and '7). At this time the porting of the valve 286 is arranged due to the spring 218 so that air under pressure is supplied to the right end of the cylinder 202 to force the piston rod 200 to the left to pivot the jaw I82 into unclamping position. Due to the action of the spring 254 the ports of the valve 246 are so located that the piston rod I40 is forced upwardly. Upward movement of the arm 48 is limited by the stop 66 so that the lever or arm I I2 is pulled upwardly by the piston rod I40 and pin I 42 to force the rear end of the arm H2 and the cam II6 downwardly. The cam thus forces the roller I20 and the rear end of the clamping lever II8 against the action of the spring I22 (Figs. 2 and 5). This holds the jaw I28 away from the jaw 82 as seen in Fig. '7. A tab is fitted within the recess 226 and will abut against the bottom end thereof to prevent it from falling out. A resistor, complete except for the tabs is placed on the mandrel 14 with the projection 30 of the band 26 abutting against the clamping surfaces 232 and 234 of the jaw 82. In most cases the resistor has been coated with a vitreous enamel and fired, so that the tab surface is oxidized. To present a clean welding surface, the end of the projection is clipped of! prior to placement of the resistor on the mandrel. The operator next pushes the pushbuttons 286 and 288 simultaneously. As noted previously, the switches are sufiiciently far apart that both hands must be used as is indicated by R and L on Fig. 18. This completes the circuit through solenoids 252 and 216 to reverse the porting through the valves 246 and 266 respectively, to force the piston rod I40 down and the piston rod 208 to the right. The movement of the piston 208 to the right allows the spring I94 to force the jaw I82 into clamping relation with the body I16 to grip the tab .36 as may be seen in Fig. 8. The spring accommodates any variations in thickness between tabs. Downward movement of the piston rod I40 first pivots the arm II2 counterclockwise as seen in Fig. 6 to move the cam II6 (Figs. 2 and 5) upward to allow the spring I22 to move the body I28 into clamping relation with the body 82 to clamp the extension 30 of the resistor terminal band 28 A A A 4" /44 oxidized surfaces thereof, with the spring I22 accommodating any variations in thickness between projections.

As the piston rod I40 continues its downward movement the pivoting of the arm I22 rotates the shaft I08 until the finger I06 strikes the stop I04. This stops the pivoting of the arm II2 and the arm 48 is moved downwardly about its pivot to lower the head I2 and force the terminal band extension 30 against the tab 36 (Figs. 3, 6, and 8). The jaws I14 and I82 are forced downwardly a short distance against the action of the spring I62. The spring allows the band projection and tab to be forced into firm engagement without crushing or bending either the extension or the tab. At the same time the solenoids 252 and 216 are energized, the motor 284 is started in operation to drive the switch arm 290. The switch arm moves over the insulating or non-connecting contact 296 during the clamping of the terminal band extension and the lug or tab and the downward movement of the head to bring the extension and tab into resilient contact. After leaving the contact 296 the arm simultaneously contacts the arcuate contacts 298, SIG, 320 and 324. This energizes the auxiliary switch solenoid 304 to complete the motor circuit independently of the push button switches 286, 280 and at the same time lights the pilot light 3I4 to inform the operator that he can release the push button switches after this time as there is no further clamping or moving together of parts to endanger the operators safety. arcuate contacts are engaged, the welding current starts, the hydrogen jet is turned on and the spark igniter becomes operative to ignite the hydrogen jet. After a short time the arm 290 leaves the contact 324 so that the spark igniter becomes inoperative but remains on the other contacts so that the motor, welding current and hydrogen jet remain in operation. After a predetermined interval, the switch arm leaves the contact 3I6 and the welding current is turned 01f. The motor circuit and hydrogen jet relay circuit are still completed for a short interval after which the hydrogen jet is extinguished as the switch arm leaves the contact 320. The arm still contacts the contact 298 at this time to continue the motor in operation. As the arm 290 leaves the contact 298 the auxiliary switch relay 304 is deenergized to stop the motor and the pilot light 3I4 is extinguished. The spring 218 retracts the plunger 214 to actuate the valve 266 to admit air under pressure to the right end of the cylinder 202 to force the roller 2I2 against the cylindrical member 2; to pivotally move the jaw I82 out of clamping relation with the jaw I14. At the same time the spring 254 retracts the plunger 250 to operate the valve 246 to admit air to the lower end of the cylinder I30 and force the piston rod I40 upwards.

The upward movement of the piston rod I40 along with the restoring force of the spring 50 forces the arm 48 upwards until it strikes its stop 66. When the arm 48 is stopped, the piston rod I40 continues to exert an upward force on the arm II2 which causes the cam II6 (Figs. 2 and 5) to react against the roller I20 and pivot the lever I I8 to move the jaw I28 away from the jaw I82. Upward movement of the piston rod 140 is stopped when the finger I00 strikes the stop I02. When it is considered that the piston Simultaneously as the several rod I40 moves rectilinearly and any point on the arm II2 moves in a compound angular motiondue to the pivoting of the arm II2 on the shaft I08 and the pivoting of the arm 48 on its pintle 50, the necessity of the slot I44 and pin I42 rather than a simple pivotal connection is obvious. When the head '12 reaches its upper limit'the resistor 20 may be removed from the mandrel I4 and reversed to weld on another tab, or another resistor may be placed on the mandrel.

It should now be apparent that with the resistor and manufacture thereof herein shown and described, a plurality of resistors may be supplied with standard terminal bands of metal having a suitable coefiicient of expansion to cooperate with the resistor core 22 and any of a wide number of different tabs suitably pre-timed the operation is entirely automatic once the tabless resistor and tabs have been placed inthe apparatus and the operator has pushed the actuating buttons. The resilient mounting of the tab nest insures proper follow-up welding pressure between the parts, and the parts are always properly aligned so that a proper butt weld may be formed.

The claims in this case are directed to the welding apparatus. Claims to the resistor are presented in a divisional application.

Although certain specific embodiments of my invention have been shown and described herein,- it is to be understood that these are for 11- lustrative purposes only and that my invention is to be limited only within the spirit and scope of the following claims.

T I claim:

, l. Mechanism for manufacturing resistors comprising a base, an arm pivotally mounted on said base, rotatable means carried by said arm, means on said arm for supporting the projection of a metallic encompassing band on a resistor, means on said base for supporting a terminal to be welded onto said projection, means for rotating the rotatable means on said arm, means responsive to rotation of said rotatable means to operate the projection supporting means to sup port a projection, means effective after a predetermined degree of rotation of said rotatable means to pivot said arm to bring said projection and said terminal into contact, and means for welding said terminal to said projection.

2. Mechanism as set forth in claim 1 wherein the means effective upon predetermined rotation of said rotatable means to pivot said arm comprises a radial projection on said rotatable means and a fixed member on said arm engageable by said projection.

3. Mechanism as set forth in claim 2 wherein the means for supporting said projection comprises a clamp and the means for rendering the clamp effective to support a projection includes a cam.

4. Mechanism as set forth in claim 1 wherein the projection supporting means comprises confronting jaws having thin gripping edges for engaging a projection without encountering a resister, and the terminal supporting means includes a pair of jaws resiliently urged toward the projection engaging jaws, resilient means normally urging the terminal jaws into engagement, and power means for opening said terminal jaws, both pairs of jaws having means for accurately positioning the projection and the terminal respectively.

5. Mechanism for welding a terminal onto a metallic projection of a resistor, comprising a pair of opposed jaws for gripping a resistor projection, said jaws having corresponding extending portions for accurately positioning a projection, means for closing said jaws on a resistor projection, a pair of opposed jaws for gripping a terminal to be welded on to said projection, one of said terminal gripping jaws having a recess for receiving and accurately positioning a terminal, and the other terminal jaw having a projection adapted to extend into said recess to grip a terminal, means for closing the terminal jaws on a terminal, means for relatively shifting the pairs of jaws toward one another to bring said terminal into engagement with said projection, and means for welding said terminal on to said projection.

6. Mechanism for applying a terminal to a projection on a resistor, and comprising means for clamping the terminal, a support assembly for the resistor, means for mounting said terminal clamping means and said resistor support assembly for relative movement to bring the terminal and resistor projection into contact, drive mechanism for effecting the relative movement between the resistor support assembly and terminal clamping means, clamp means associated with said resistor support assembly for separately clamping the resistor projection, means operable in response to operation of the drive mechanism for actuating said clamp means for independent movement relative to said resistor support assembly to clamp the resistor projection and operable tomaintain the resistor projection in clamped position during contact thereof with the terminal, and means for welding the resistor projection to the terminal during contact.

7. Mechanism as claimed in claim 6, wherein the resistor support assembly includes a stud-like member internally engaging and supporting the resistor.

8. Mechanism as claimed in claim 6, wherein means are provided for maintaining the terminal and resistor projection resiliently in contact with one another during welding.

9. Mechanism as claimed in claim 6, wherein actuation of the clamp means for clamping the resistor projection is effected prior to relative movement between the resistor support assembly and the terminal clamping means.

10. Mechanism as claimed in claim 6, wherein 12 the resistor support assembly and associated clamp means are movable toward and away from the terminal clamping means.

11. Mechanism as claimed in claim 10, wherein the terminal clamping means is resiliently mounted to provide resilient contacting pressure between the terminal and resistor projection.

12. Mechanism as claimed in claim 6, wherein there is provided a releasable connection between the drive mechanism and the clamp means effective to permit relative independent movement of the clamp means with respect to the support means for clamping and unclamping the resistor projection.

13. Mechanism as claimed in claim 6, wherein the drive mechanism includes a lost motion connection with the support assembly and a releasable inter-engaging connection with said clamp means effective upon release to permit clamping movement of the clamp means during the lost motion cycle of the drive mechanism.

14. Mechanism as claimed in claim 6, wherein the clamp means for the resistor projection is resiliently maintained in one position, and wherein the drive mechanism includes a releasable connection with the clamp means eifective to permit movement of the clamp means to its other position.

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